A vapor deposition apparatus for manufacturing an epitaxial silicon wafer has been known (see, for instance, Patent Literature 1).
The apparatus disclosed in Patent Literature 1 includes a wafer-transfer chamber in an atmosphere of nitrogen gas, a reaction chamber in an atmosphere of hydrogen gas and a partition-moving mechanism therebetween, where the partition-moving mechanism is opened to introduce the nitrogen gas present in the wafer-transfer chamber into the reaction chamber while the pressure in the wafer-transfer chamber is set higher than the pressure in the reaction chamber. Then, after transferring a silicon wafer received in the wafer-transfer chamber into the reaction chamber, a silicon epitaxial film is formed on the silicon wafer while the partition-moving mechanism is closed and the supply of the nitrogen gas into the reaction chamber is stopped.